THE HESSIAN FLY, 19 
run over the field and the mown grass, weeds, and stubble allowed to 
dry for a few days just before the burning. This is much the more 
feasible measure in the Northwest, and ought to be more generally 
followed. 
DESTRUCTION OF VOLUNTEER WHEAT. 
Perhaps the importance of the destruction of volunteer wheat is 
best illustrated by the condition frequently observed in fields of 
young wheat in the fall, where every volunteer plant is infested and 
the sown grain is entirely free from attack. The volunteer plants 
were above ground in time to enable the fly to deposit her eggs on 
them, with the result that large numbers of flaxseeds will go through 
the winter and the flies therefrom will deposit their eggs on the 
plants which constitute the crop itself. Mr.C. N. Ainslie found 157 
‘“flaxseeds’’ on a single volunteer wheat plant taken from a field in 
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Fig. 16.—Platygaster herrickii, a parasite of the Hessian fly. Much enlarged. (Original.) 
southwestern Iowa in October, 1914. Thus the growth of volun- 
teer plants menaces, to a certain degree, the crop of the following 
year, precisely as does a field sown too early more seriously menace 
adjoining fields that are uninfested in the fall. This destruction of 
volunteer plants by plowing, disking, or otherwise must take place 
before the larve have matured in order to be effective. 
ENRICHING THE SOIL. 
While it may seem “far fetched”’ to bring forward as a preventive 
measure the enrichment of the soil, a fertile soil will produce plants 
that will withstand with little injury attacks that will prove disastrous 
to plants growing on an impoverished or thin soil. This is because a 
fertile soil will enable an infested plant to tiller freely, and these tillers 
will have sufficient vitality to withstand the winter and send up head- 
producing stems in the spring. It is also chiefly on the thin or impov- 
